Sound Waves and Electric Pulses Reshape the Tomato From Cell Wall to Shelf

The tomato is one of the most processed fruits on Earth. More than 186 million tonnes are grown every year, and over 130 million tonnes of that harvest are cooked, crushed, peeled, and juiced into the sauces, purees, and juices that fill supermarket shelves. The industrial machinery of tomato processing leaves behind roughly eight million tonnes of waste annually, mostly skins and seeds, and for decades that material has been treated as little more than landfill. A new review published in Frontiers in Soft Matter argues that this picture is changing, and that two quiet, non-thermal technologies, ultrasound and pulsed electric fields, are rewriting how food engineers think about the humble tomato from its cell walls all the way up to the finished product.

Daniela Lorena Lamas of the Instituto de Investigaciones Marinas y Costeras in Mar del Plata, Argentina, examined recent advances in both technologies through what she calls a multiscale framework, connecting molecular and cellular events to the macroscopic properties that actually matter in a factory: texture, mass transfer, extraction efficiency, and the recovery of valuable bioactive compounds such as lycopene. Her central insight is deceptively simple. Although ultrasound and pulsed electric fields can both improve extraction and processing, they attack the tomato through fundamentally different structural targets, and understanding those differences is the key to designing better, more sustainable tomato products.

Ultrasound works through acoustic cavitation. When high-intensity sound waves, typically in the range of 20 to 100 kilohertz, pass through the water-rich tissue of a tomato, they generate microscopic bubbles that grow and then collapse violently. The implosion of each bubble produces localised shear forces, microjets travelling at speeds between 200 and 700 metres per second, and transient spikes in temperature and pressure. These phenomena physically rupture cell walls, tear apart middle lamella structures that hold cells together, and progressively erode tissue architecture. The result is a cascade of structural damage that propagates upward through the hierarchy of the tomato matrix, from molecular liberation of bound compounds to cellular membrane poration to tissue-scale particle fragmentation, ultimately reducing mass transfer resistance and accelerating the release of intracellular metabolites.

Pulsed electric fields, by contrast, take a surgical approach. Short bursts of high-voltage electricity, typically between 0.5 and 10 kilovolts per centimetre at moderate intensities, induce a phenomenon called electroporation. When the electric field generates a transmembrane potential across a cell membrane that exceeds a critical threshold, the phospholipid bilayer rearranges and forms nanoscale pores. The membrane becomes permeable, allowing solvents and solutes to pass freely, but the surrounding cell wall network remains largely intact. This selectivity is what makes pulsed electric fields so attractive for tomato processing. The technology can soften tissue, reduce peeling resistance, and enhance the extraction of lipophilic carotenoids without the indiscriminate thermal damage that conventional heat treatment causes.

The quantitative gains reported in the literature are striking. Optimised ultrasound-assisted extraction protocols can increase carotenoid and lycopene recovery from tomato processing residues by 40 to 50 percent while halving extraction times, and when combined with tailored encapsulation strategies the recovered compounds maintain superior stability. Pulsed electric field treatments have been shown to increase lycopene extraction from tomato waste by up to 47 percent, rising from 9.84 to 14.31 milligrams per 100 grams, while enhancing the recovery of β-carotene and β-cryptoxanthin by up to 69 and 24 percent respectively. In some studies, controlled membrane permeabilisation boosted lycopene extractability by as much as 88 percent. At the tissue level, pulsed electric field softening of the skin–parenchyma interface reduced the mechanical work required for industrial peeling by 72.3 percent while increasing juice yield by 20.5 percent.

But the review goes beyond extraction engineering. Lamas highlights emerging evidence that ultrasound can trigger complex physiological responses in living tomato tissues, not just processed ones. When applied to tomato seeds and seedlings, acoustic cavitation induces the formation of controlled reactive oxygen species, which act as cellular elicitors. These molecules upregulate the transcription of stress-responsive genes and activate antioxidant defence enzymes such as superoxide dismutase, catalase, and peroxidase. The downstream effect is a defensive biochemical shift that increases the concentration of free phenolics, ascorbic acid, and specific antioxidant fractions within the plant matrix. At the organismal level, this translates into enhanced germination rates, accelerated early seedling growth, and improved tolerance to subsequent environmental stresses such as drought.

The most provocative finding in the review concerns transgenerational plasticity. Emerging evidence suggests that ultrasound priming of tomato plants can induce epigenetic modifications that persist across subsequent plant progenies, altering drought-adaptive physiological responses in offspring that were never directly exposed to the acoustic treatment. If confirmed, this would shift ultrasound from a purely physicochemical engineering tool toward a potential modulator of biological signalling pathways, expanding the concept of structure–property relationships from dead industrial matrices to living biological systems where structural perturbations can regulate biochemical and physiological functions across generations.

Despite these advances, both technologies face significant engineering bottlenecks. Ultrasound reproducibility is highly sensitive to reactor geometry, acoustic energy attenuation, and processing configuration, complicating cross-study standardisation and pilot-scale translation. Pulsed electric field efficiency depends heavily on the electrical conductivity and physical homogeneity of the tomato matrix, making the technology well suited to pumpable purees and juices but challenging for irregular solid masses. The intrinsic biophysical properties of the tomato itself constrain both processes: tissue porosity dictates acoustic propagation, while electrical conductivity governs field uniformity. At high processing thresholds, excessive acoustic or electrical power inputs risk localised degradation of thermolabile molecules such as lycopene, and in the case of pulsed electric fields, high field intensities between 35 and 40 kilovolts per centimetre can generate localised Joule heating within the conductive tomato matrix, undermining the non-thermal nature of the process.

The analytical toolkit for monitoring these structural transitions is advancing rapidly. Scanning electron microscopy profiles surface erosion, confocal laser scanning microscopy assesses membrane integrity, and Fourier-transform infrared spectroscopy traces chemical alterations within the polysaccharide cell wall matrix. These complementary techniques provide valuable evidence of microstructural and chemical modifications, but Lamas notes that establishing quantitative structure–property relationships requires integrating these observations with complementary measurements of macroscopic properties, including rheological behaviour, texture, permeability, and mass transfer characteristics. Without that integration, the field risks accumulating descriptive data without predictive power.

The review closes with a call for predictive multiscale models that can couple cavitation physics, electroporation dynamics, and biological responses within a single framework. Such models would accelerate the design of continuous, large-scale non-thermal platforms within sustainable circular bioeconomies, where tomato waste is no longer a liability but a valuable secondary raw material rich in lycopene, phenolics, and dietary fibre. The sequential or combined integration of ultrasound and pulsed electric fields within a single cascade biorefinery layout remains an open research gap, but coupling cavitation-driven cell wall fragmentation with electroporation-mediated membrane permeabilisation offers a promising pathway for efficient, solvent-free process intensification. For an industry processing more than 130 million tonnes annually, the difference between treating tomato waste as landfill and treating it as a bioresource may come down to how precisely engineers can control the structural hierarchy of the fruit itself.

Subject of Research: Tomato processing

Article Title: Multiscale structural effects of ultrasound and pulsed electric field processing on structure–property relationships in tomato systems: a mini-review

Article References: Lamas, D. L. (2026). Multiscale structural effects of ultrasound and pulsed electric field processing on structure–property relationships in tomato systems: a mini-review. Frontiers in Soft Matter, 6, Article 1887216. https://doi.org/10.3389/frsfm.2026.1887216

Image Credits: AI Generated

DOI: 10.3389/frsfm.2026.1887216

Keywords: Multiscale, structural, effects, ultrasound, pulsed, electric, field, processing, structure, property, relationships, tomato